<?php
/**
 * Created by PhpStorm.
 * User: Administrator
 * Date: 2017/9/18
 * Time: 16:19
 */
//$arr = [
//    'name'=>'frank',
//    'age'=>19,
//    'nickName'=>'frank'
//];
$arr = [

    'tom','frank','jack'
];

$brr = array_keys($arr);
var_dump($brr);//去掉了了nickName

$arr = [

    'first'=>'tom','second'=>'frank','jack'
];

$brr = array_keys($arr);
var_dump($brr);//去掉了了nickName